Ignition system for electrical discharge lamps



Oct. 18, 1966 NANAO TODA ETAL IGNITION SYSTEM FOR ELECTRICAL DISCHARGELAMPS Filed 001;. 23. 1963 FIG.

FIG. 3

United States Patent 3,280,371 IGNITION SYSTEM FOR ELECTRICAL DISCHARGELAMPS Nanao Toda, Yoshishige Tokui, and Yoshio Kurokawa, Tokyo, Japan,assignors to Iwasaki Denki Kabushiki Kaisha, Tokyo, Japan Filed Oct. 23,1963, Ser. No. 318,315 Claims priority, application Japan, Get. 26,1962, 37/ 47,751 9 Claims. (Cl. 315-290) This invention relates to alighting means for the instantaneously relighting of discharge lamps.Generally, ifor relighting a discharge lamp, such as a high voltagemercury lamp, soon after having once been extinguished, a lowering ofgaseous atmospheric pressure due to temperature decrease of saiddischarge lamp has to be awaited. It requires several minutes or a fewminutes above ten. Accordingly, as a means for relighting the dischargelamp after having once been extinguished, means for an instantaneouslyapplying high voltage or pulses are usually adopted.

It is a first object of the present invention to provide a lightingapparatus for discharge lamps wherein a discharge lamp isinstantaneously relighted by imparting a high voltage pulse generated ina pulse circuit to said discharge lamp.

A second object of the present invention is to perform a rapid and exactopening operation of a high voltage pulse circuit by connecting astabilizing circuit to said high voltage pulse circuit, that is, oncethe lighting of the discharge lamp is effected, and immediatelythereafter automatic change-over of the system to the stabilizingcircuit is effected in order to perform the opening of the high voltagepulse circuit rapidly and exactly.

Further, a third object of the present invention is to prevent inadvance the occurrence of pulse by opening the high voltage pulsecircuit with a slight delay after an electric source being connected, soas to eliminate the effect of back flow of pulses upon a safety deviceand other devices on the side of the electric source, in case of thecircuit being unable to start due to disturbance of the discharge lamp.

In the following, the present invention is described in detail inconnection with the accompanying drawings, in which FIG. 1 is a wiringdiagram for the apparatus of the present invention adapted to open ahigh voltage pulse circuit by melting down a fuse in order to avoiddisturbances from high voltage pulse when the discharge lamp is unableto be lighted;

FIG. 2 is a wiring diagram for the apparatus of the present inventionadapted to automatically perform the opening of the high voltage pulsecircuit of above-mentioned FIG. 1: and

FIG. 3 is a part of the modified relay wherein the primary coil of therelay in the apparatus illustrated in FIG. 2 is replaced by a decreasein voltage due to resistance.

Referring to FIG. 1 of the accompanying drawings, by 1 is meant aleakage transformer, namely a stabilizing device; 2 an induction coil; 3a vacuum switch; 4 a gap; 5 a protection gap; 6 a discharge lamp; 7 achoke coil; 8 an exciting coil; 9 relay switch contacts; 10 a fuse; 11an electromagnetic safety device; 12 and 13 condensers inserted in thesecondary winding of stabilizing device 1; 14 a condenser inserted inthe primary winding of stabilizing device 1; and a pulse circuit isconsisted of the secondary winding 15fuse Ill-relay switch contacts9induction coil 2vacu um-switch 3the secondary winding 15 of stabilizingdevice 1.

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When a switch 19 for the electric source is closed, a voltage will beinduced in the secondary Winding 15 of stabilizing device (a leakagetransformer) 1, and an electric current will flow along a circuit paththrough the fuse metal (or low fusion point metal) 10, switch 9,induction coil 2, vacuum switch 3, stabilizing device 1. In this case,the induction coil 2 acts as an exciting coil for the vacuum switch 3 tocut off and disconnect the current passing through above-mentionedcircuit. A back electromotive force occurring then causes a sparkdischarge across the gap 4 resulting in a hi h voltage pulse betweenboth terminals of discharge lamp 6. Accordingly, the discharge lamp 6commences to make an arc discharge, and then electric current begins topass through a stable circuit traced from the secondary winding 15 ofstabilizing device 1, exciting coil 8, choking coil 7, discharge lamp 6,and back to the secondary coil 15 of stabilizing device 1. As a result,the exciting coil 8 is excited to open the switch 9 inserted in thepulse circuit and stop the occurrence of pulses. In such instance, thepulse circuit is opened 'in to & second after current is passed.

The foregoing description relates to the case when the discharge lamp 6is lighted normally. However, when the lamp 6 becomes unable to startfor some cause, the pulse circuit should be opened quickly to stop theoccurrence of pulses. In order to avoid bad effects of pulses upon otherelements of apparatus during the time from the occurrence of pulses tothe opening of the pulse circuit, the protection gap 5 is connected inparallel to the discharge lamp 6. Even more, it is preferable that theoccurrence of pulses be stopped even earlier. Therefore, according tothe present invention, the pulse circuit is connected with the fusemetal 10 in series, and when the discharge lamp 6 does not start, thepulse circuit is adapted to be spontaneously opened after elapse of apredetermined interval of time.

Accordingly, a fuse-metal melting due to an electric current nearlyequivalent to a short circuiting current for the pulse circuit is used,and fuse metal 10 is adapted to melt down with a time-difference ofapproximately /a to /2 second after the electric source being connectedthereto.

Furthermore, according to the present invention, the electromagneticsafety device 11 is provided to prevent reflected pulses from being fedback toward the electric source. Namely condensers 17 and 18 areconnected to both lines of the primary winding 16 of the stabilizingdevice 1 to constitute the safety device 11 for by-passing the reflectedpulse to a point of reference potential.

The other embodiment of the present invention illustrated in FIG. 2 isarranged to use a time-limit opening device for the purpose of openingthe pulse circuit when the discharge lamp 6 does not start. An excitingcoil 20 corresponding to the exciting coil 8 shown in FIG. 1 is designedto constitute the primary winding of a transformer 21, of whichsecondary winding 22 constitutes a relay coil for operating achange-over switch 23 between the pulse circuit and the stabilizingcircuit. In addition, a winding 27 operated with above-mentionedsecondary winding 22 is connected with the electric source, in serieswith a glow lamp 24, and a resistance 25 is connected to the winding 27in a parallel. When this resistance 25 is disconnected from the circuita switch 26' is operated to short circuit the glow lamp 24; suchdisconnection occurs because the switch 26 is interlocked with saidswitch 23.

Now, on the occasion of close-circuiting the switch 19 to the electricsource, a high voltage pulse is generated by a circuit for thestabilizing device 1 passing through the stabilizing device 1,change-over switch 23, contact 230, induction coil 2, vacuum switch 3,stabilizing device 1; whereupon the high voltage pulse is applied to thedischarge lamp 6 to start arc discharge and consequently letting astable current begin to flow through the stabilizer 1, primary winding(induction coil) 20, choking coil 7 and discharge lamp 6. Thus thechange-over switch 23 is changed from the contact point 23a over tocontact point 23b by means of the secondary winding 22 of transformer21, that is, the stabilizing device circuit is closed by disconnectingthe high voltage circuit of pulse.

Through the primary winding 21} is short-circuited by the changing-overof change-over switch 23 to a contact point 23b, and in this instance,the switch 26 interlocked with switch 23 also changes from a normalposition of contact point 26a over to a contact point 261), the winding27 remains connected to the electric source, maintaining the closingcircuit of change-over switch 23 to the contact point 23b and,accordingly, maintaining the lighting condition of discharge lamp 6.

In case of an accident of discharge lamp 6 or other disturbances atabove-mentioned starting, an electric discharge begins to take placeacross the protection gap which is connected in parallel to thedischarge lamp 6, protecting the circuit from high voltage pulses. Thestarting voltage of protection gap 5 should be higher than that ofdischarge lamps 6. In consequence, since it is necessary to open thepulse circuit after a certain time limit as similarly as in the case ofthe fuse being melted down, the change-over switch 23 does not changeover to contact point 2%, unless the stable current passes throughwinding and of course, the switch 26 does not change over to contactpoint b. Therefore, a voltage is applied to the glow lamp 24 throughresistance 25, and the glow lamp 24 commences to discharge. At first,the electric current passing through the winding 27 is minute andinsufiicient to operate the switch 23. Thereafter, when the insidecontact point of the glow lamp 24 is :closed after a predetermined timeinterval, for instance, 0.3 to 1 second delay, a heavy current will flowthrough the winding 27. The change-over switch 23 is operated by suchcurrent to open the pulse circuit, and simultaneously the switch 26 istransferred to the contact point 26b; therefrom the glow lamp 24 isshort-circuited to open, which condition is maintained until the circuitof electric source switch is opened. Thus, bad influences due to highvoltage pulse can be avoided.

The pulse circuit is protected from electric current of the stabilizerdevice passing through the pulse circuit, by by connecting the gap 4 inseries to discharge lamp 6. Furthermore, the entrance of the electriccurrent from the stabilizing device side into the pulse circuit isdisturbed by means of lower filtering devices (7, 12, 13, 28). Even if ahigh voltage should occur in the primary winding side of stablizingdevice 1, there would occur almost no hinderances to affect other parts,since condensers 29, 30 and 31 are inserted for prevention.

In some cases, in addition to the induction coils 2, an exciting coil ofthe vacuum switch 3 may be provided separately. Instead of the primarywinding 20 of the clay transformer 21 of FIG. 2, a resistance 33 of FIG.3 may be used, thereby the change-over switch 23 being acutated bychange of magnetic fluxes 34 due to lowering of the voltage.

What we claim:

1. A starting and operating system for a discharge lampadapted to beoperated from a transformer having a primary and secondary winding inwhich said primary winding is coupled to a power source, comprising incombination:

a starting circuit coupled to said discharge lamp by means of saidsecondary winding and including a first set of relay contact meanshaving a normally open and a normally closed pair of contacts, aninduction coil coupled in .series to said aforementioned normally closedpair of contacts between said secondary winding and said discharge lamp,and a normally closed vacuum switch responsive to the energised state ofsaid induction coil, being coupled in parallel with said discharge lampand becoming non-conductive in response to the energized state of saidinduction coil to produce an electrical starting siginal for energisingsaid discharge lamp;

an operating circuit coupling said secondary winding to said dischargelamp comprising first relay coil means and ballast means connected inseries between said secondary winding and said discharge lamp, saidfirst relay coil means being operative to open said aforementionednormally closed pair of contacts to provide an open circuit in saidstarting circuit when said operating circuit is energizing saiddischarge lamp;

and protective circuitry for said system in the event said startingcircuit fails to operate comprising, second relay coil means for openingsaid aforementioned normally closed pair of contacts, an electricaltiming device having a predetermined time delay coupled to said secondrelay coil means for energizing said second relay coil means after saidpredetermined time delay, circuit means coupling said timing device andsaid second relay coil means across said power source, and a second setof relay contact means simultaneously operable with said first set ofrelay contact means and having a normally open and normally closed pairof contacts, said second set of relay contact means coupled across saidtiming device whereby said open pair of contacts will short said timingdevice thereby rendering said timing device inoperative when said secondrelay coil means becomes energized.

2. Apparatus as defined by claim 1, wherein said protective circuitryincludes a third relay coil magnetically coupling said first and saidsecond relay coil means.

3. Apparatus as defined by claim 1, wherein said timing device comprisesa glow lamp.

4. Apparatus as defined by claim 3, wherein said protective circuitryadditionally includes resistance means coupled in parallel across saidsecond relay coil means by means of said normally closed contacts ofsaid second set of relay contact means.

5. A starting and operating system for a discharge lamp powered from anelectric source comprising in combination:

transformer means having a primary and a secondary winding includingmeans for coupling said primary Winding to said electric source;

a starting circuit including said discharge lamp coupled across saidsecondary Winding comprising, a pair of normally closed relay switchcontacts, vacuum switch energization means connected in series to saidnormally closed relay switch contacts, gap means connected in seriesbetween said vacuum switch energization means and said discharge lamp, avacuum switch adapted to be operated by said vacuum switch energizationmeans and being coupled across said gap means and said discharge lamp,becoming nonconductive in response to the operation of said energizationmeans to provide an open circuit thereacross, thereby causing an arcdischarge to occur across said gap means to start said discharge lamp;

an operating circuit for said discharge lamp after starting comprising,a relay coil for actuating said pair of normally closed relay switchcontacts in said starting circuit, circuit means coupling said relaycoil to said secondary winding, ballast means coupled in series betweensaid relay coil and said discharge lamp, said relay coil being operableto open said normally closed relay switch contacts to render saidstarting circuit inoperative when said discharge lamp has been started.

6. Apparatus as defined by claim 5, and including a protective circuitfor said system in the event said starting circuit fails to operatecomprising, another relay coil for actuating said normally closed relayswitch contacts, an electrical timing device having a predetermined timedelay coupled to said another relay coil for energizing said relay coilafter said predetermined time delay, circuit means coupling said timingdevice and said another relay coil across said power source, a pair ofnormally open relay contacts adapted to be actuated by both said relaycoils, being connected across said timing device for rendering saidtiming device non-conductive when said second relay coil becomesenergized.

7. Apparatus as defined by claim 6, wherein said timing device comprisesa glow lamp.

8. Apparatus as defined by claim 6, wherein said timing device comprisesa glow lamp having a predetermined time delay greater than the timenecessary to start said discharge lamp by means of said startingcircuit.

9. Apparatus as defined by claim 6, wherein said protective circuitadditionally includes another pair of normally closed relay contactsadapted to be actuated by both .said relay coils and resistance meanscoupled in parallel across said another relay coil by means of saidanother pair of normally closed relay contacts.

References Cited by the Examiner UNITED STATES PATENTS 1,984,489 12/1934Mutsaers 315100 2,103,030 12/ 1937 Dorgello 315290 2,434,768 1/ 1948Johnson et al 315-100 2,462,306 2/ 1949 Cook 315100 2,557,809 6/1951Willoughby 315100 2,825,005 2/1958 Bird 315289 FOREIGN PATENTS 751,7817/ 1956 Great Britain.

JOHN W. HUCKERT, Primary Examiner.

A. M. LESNIAK, Assistant Examiner.

5. A STARTING AND OPERATING SYSTEM FOR A DISCHARGE LAMP POWERED FROM ANELECTRIC SOURCE COMPRISING IN COMBINATION: TRANSFORMER MEANS HAVING APRIMARY AND A SECONDARY WINDING INCLUDING MEANS FOR COUPLING SAIDPRIMARY WINDING TO SAID ELECTRIC SOURCE; A STARTING CIRCUIT INCLUDINGSAID DISCHARGE LAMP COUPLED ACROSS SAID SECONDARY WINDING COMPRISING, APAIR OF NORMALLY KCLOSED RELAY SWITCH CONTACTS, VACUUM SWITCHENERGIZATION MEANS CONNECTED IN SERIES TO SAID NORNALLY CLOSED RELAYSWITCH CONTACTS, GAP MEANS CONNECTED IN SERIES BETWEEN SAID VACUUMSWITCH ENERGIZATION MEANS AND SAID DISCHARGE LAMP, A VACUUM SWITCHADAPTED TO BE OPERATED BY SAID VACUUM SWITCH ENERGIZATION MEANS ANDBEING COUPLED ACROSS SAID GAP MEANS AND SAID DISCHARGE LAMP, BECOMINGNONCONDUCTIVE IN RESPONSE TO THE OPERATION OF SAID ENERGIZATION MEANS TOPROVIDE AN OPEN CIRCUIT THEREACROSS, THEREBY CAUSING AN ARC DISCHARGE TOOCCUR ACROSS SAID GAP MEANS TO START SAID DISCHARGE LAMP; AN OPERATINGCIRCUIT FOR SAID DISCHARGE LAMP AFTER STARTING COMPRISING, A RELAY COILFOR ACTUATING SAID PAIR OF NORMALLY CLOSED RELAY SWITCH CONTACTS IN SAIDSTARTING CIRCUIT, CIRCUIT MEANS COUPLING SAID RELAY COIL TO SAIDSECONDARY WINDING, BALLAST MEANS COUPLED IN SERIES BETWEEN SAID RELAYCOIL AND SAID DISCHARGE LAMP, SAID RELAY COIL BEING OPERABLE TO OPENSAID NORMALLY CLOSED RELAY SWITCH CONTACTS TO RENDER SAID STARTINGCIRCUIT INOPERATIVE WHEN SAID DISCHARGE LAMP HAS BEEN STARTED.